bonding: Remove debug_fs files when module init fails

Remove the bonding debug_fs entries when the
module initialization fails. The debug_fs
entries should be removed together with all other
already allocated resources.

Signed-off-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: Jay Vosburgh <j.vosburgh@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>